1. Field of the Invention
This invention is concerned with a method of coating cutting edges, more particularly razor blade cutting edges, with fluorocarbon polymers.
2. Description of Related Art
For many years razor blade cutting edges have been coated with polyfluorocarbons, more particularly polytetrafluoroethylene (PTFE); see, for example, British Specification 906005. The polyfluorocarbons used for this purpose are telomers, that is they are polymers having a relatively low molecular weight. Thus the PTFE conventionally used for the coating of razor blade cutting edges has a molecular weight of about 25000, as compared with PTFE which is conventionally used for the formation of non-stick coatings which has a molecular weight of 3-6 million.
The reason for using fluorocarbon telomers rather than high molecular weight materials for coating cutting edges is that the former give improved blade-to-blade uniformity and coatings of improved durability.
Polyfluorocarbons, such as PTFE, are conventionally made by polymerization of the monomer in an aqueous dispersion and this gives rise to the high molecular weight material referred to above. Fluorocarbon telomers are made by polymerization in a chlorofluorocarbon, such as trichlorotrifluoroethane. However, in view of mounting pressure on industry for environmental reasons to eliminate the use of CFCs in manufacturing processes and in products, there is a need to use an alternative process for making fluorocarbon telomers.